gnome-cups-manager shows only the 'default sign' on the system-default printer right clicking on a printer, as user, and making it default works (i can confirm that by lpoptions), but the 'default sign' does not show the changes.
Created attachment 198164 [details] emerge --info # qlist -Iv cups net-print/cups-1.3.10-r1 net-print/gnome-cups-manager-0.33-r1 net-print/libgnomecups-0.2.3
sounds like something to report to upstream.
gnome-cups-manager will be removed in 30 days, use system-config-printer-gnome instead